In some cases, the atmosphere contains corrosive gases that corrode electronic devices. The emission sources of the corrosive gases include a chemical plant such as a paper mill and a rubber factory, a waste treatment plant, a sewage treatment plant, a volcano, commodities containing chemicals, and the like.
One of the corrosive gases emitted from such emission sources is hydrogen sulfide gas. The hydrogen sulfide gas can corrode wires in an electronic device and break the electronic device. Particularly, in the case where an information society uses electronic devices to support the foundation of the system in social infrastructure, breakdown of the electronic devices may paralyze social activities.
In order to prevent breakdown of electronic devices due to the corrosive gas, it is useful to monitor the corrosive gas contained in an environment where the electronic devices are installed and to know in advance a possibility of the electronic devices breaking down due to corrosion caused by the corrosive gas.
A QCM (Quartz Crystal Microbalance) sensor is known as a sensor to monitor the corrosive gas. The QCM sensor is a mass sensor capable of measuring a minute change in mass by using a property that, when the mass of electrodes on a crystal oscillator is changed by corrosion, the crystal oscillator reduces its oscillation frequency according to the amount of the corrosion.
In the QCM sensor, a change in the oscillation frequency grows as the amount of corrosion is increased over time, and the QCM sensor comes to the end of its life. For this reason, in the case of monitoring the corrosive gas over a long time period, it is preferable that a QCM sensor whose life is close to the end be replaced with a new QCM sensor to prevent a blank period in monitoring.
However, since QCM sensors have individual differences, the replaced QCM sensor cannot necessarily maintain the measurement accuracy for the amount of corrosion caused by the corrosive gas.